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The pituitary gland is a vital organ with many functions. It is a very complicated organ. We will just touch it's basic functions relating to the regulation of the female reproductive organs.

It is important to understand the principle of negative feedback to be able to understand the regulatory function of this gland . The thermostat controlling the geaser that supply hot water to our homes works on this principle.(negative feedback). Imagine that the thermostat is set to 60 degrees Celcius. If the tmeperature of the water rises above 60 degrees the power supply is cut but if the temperature goes below 60 degrees the thermostat reconnects the power.

The pituitary works on the same principle. It produces two hormones that stimulate the ovaries to produce oestrogen. The two hormones are known as FSH (Folicle Stimulating Hormone) and LH ( Luteinising Hormone). If the oestrogen levels are low the pituitary gland produces more FSH and LH . The FSH and LH stimulate the ovary and it producesmore oestrogen. If the oestrogen levels are high the pituitary gland produces less FSH and LH and hence the ovary produces less oestrogen. In a normal healthy female the oestrogen , FSH and LH levels are regulated within narrow margins.

The next diagram illustrates the relationship between the ovaries and pitiutary.

If the oestrogen goes up the FSH and LH go down and vice versa. It is important to remember that oestrogen is formed in the follicle (see The Normal Ovary). FSH is a abbeviation of follicle stimulating hormone and LH of luteinsing hormone. It is necessary for the formation of the yellow body the CORPUS LUTEUM. Both FSH and LH are necessary for the normal development of the follicle and ovulation. It is also important that their levels are regulated by the negative feedback effect of oestrogen within certain limits.

Following ovulation , the corpus luteum appears . It has a limited live span and LH plays a posible role in its function. Normal LH levels levels won't be able to expand this live span beyond ten days.

In the condition known as polycystic ovarian syndrome (PCO) the LH levels are usually increased.

After the menopause the ovaries ceased to produce oestrogen and the FSH and LH levels become very high in an effort to stimulate the non responding ovaries (see MENOPAUSE).

The pituitary also produces another important hormone called PROLACTIN. One of prolactin's most important functions is stimulating the breasts to produce milk. Excessive prolactin production in non lactating women causes ovarian dysfunction with anovulation ( the ovary stops producing egg cells).

The hormones produced by the pituitary gland isalso under the control of hormones produced by the hypothalamus part of the brain. The pituitary gland is attached to the hypothalamus via a stalk as illusrated in the previous drawing.

It is important to know that another name for the pituitary gland is the hypophysis

The hormones secreted by the hypothalamus that regulates the hormone secretion by the pituiraty gland, is known as releasing hormones

The one hypothalamic releasing hormone of importance regarding the current discussion, is the gonadottropin-releasing hormone (Gn-Rh). This hormone is responsible for the release of FSH and Lh by the pituitary gland .

Medicines that suppress the release of Gn-Rh are used in the treatment of certain female coonditions where a decrease in the oestrogen levels are indicated. Zolodex (generic name goserelin) is the name of the drug.

The following drawing illustrates the positions of the pituitary gland ((hypophysis) and the hypothalamus and their relationship to the brain.

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